Apparatus for evaluation of skin impedance variations

ABSTRACT

The invention provides an apparatus and method for automatic evaluation of skin resistance or impedance variations in order to diagnose the state of health of at least a portion of a human or animal body. The difference between an AC impedance measured at a specific frequency and at a specific skin area with calibration electrode and a reference electrode and the impedance measured at a similar frequency and in the same area with a measurement electrode and a reference electrode, is used to determine the state of health of the internal organ corresponding to the examined skin area. Alternatively, the skin between the electrodes is exposed to a DC potential of a magnitude selected to give a breakthrough effect. The resistance of the skin is measured between a measurement electrode polarised negatively with respect fo a reference electrode, and the DC resistance of the same skin area is again measured but with the measurement electrode polarised positively with respect to the reference electrode. The ratio of these two values is used to determine the state of health of the internal organ corresponding with the examined skin area.

BACKGROUND TO THE INVENTION

[0001] This invention relates to an apparatus and method for automaticevaluation of skin impedance variations in order to estimate the stateof health of the internal organs of a human or animal.

[0002] Existing methods of utilising skin impedance values for organdiagnostics base their results on non-ratiometric measurements of basicskin impedance and produce inconsistent and unreliable results whichdepend on numerous variables, including the emotional state of thepatient, muscular tension, measurement time, the contact area andpressure of the measuring electrode and various physiologicaldifferences between individuals.

[0003] After many years of research the inventor now believes that theinternal organs of the body of a human or animal have correspondingareas on the skin where information regarding the corresponding internalorgans can be retrieved by measuring the electrical properties of saidskin. The inventor further believes that said corresponding areas of theskin have other properties related to the science of reflexivepyhsiotherapy (including acupuncture), for example, the ability to healand/or relieve pain caused by the corresponding organs.

[0004] The inventor believes yet further that these corresponding areasof the skin may be mapped, which map is applicable to variousindividuals

[0005] The inventor has found that the ear auricle may be particularlyaccurately mapped and is most suitable for the method of the inventionsince in most cultures the skin of the ear is exposed and may beexamined without any garments having to be removed.

[0006] In this specification, unless the context clearly indicates tothe contrary, the term “impedance”, is to be understood to includeresistance.

SUMMARY OF THE INVENTION

[0007] The impedance variation can be measured in two ways:

[0008] Method 1. AC evaluation.

[0009] The difference between the AC impedance measured at a specificfrequency and at a specific skin area with a calibration electrode and areference electrode and the impedance measured at a similar frequencyand in the same area with a measurement electrode and a referenceelectrode, is used to determine the state of health of the internalorgan corresponding to the examined skin area. The calibration electrodeand reference electrode contact areas are relatively larger than themeasurement electrode skin contact area.

[0010] Method 2: DC evaluation

[0011] The term “break-through effect” refers to the sudden andsignificant drop in skin electrical resistance witnessed after asufficient potential difference is applied between the electrodes.

[0012] The skin between the electrodes is exposed to a DC potential of amagnitude selected to give the break-through effect. The DC resistanceof the skin is measured between a measurement electrode polarisednegatively with respect to a reference electrode, and the DC resistanceof the same skin area is again measured but with the measurementelectrode polarised positively with respect to the reference electrode.The ratio of these two values is used to determine the state of healthof the internal organ corresponding with the examined skin area.

[0013] An apparatus broadly in accordance with the invention may includethe following functional blocks:

[0014] A measurement and/or calibration electrode, a referenceelectrode, a voltage generator block, a measurement block. a controlblock, a user interface block, a result presentation block and,optionally, a data storage block.

[0015] The voltage generator block generates a potential differencebetween the measurement electrode and the reference electrode, or thecalibration electrode and the reference electrode. The voltage generatorblock is connected to and controlled by the control block. Themeasurement block is connected to the measurement electrode and thereference electrode (FIG. 1).

[0016] The measurement block determines the impedance between themeasurement electrode and the reference or calibration electrode.Alternatively the voltage generator block can be connected through themeasurement block to the measurement electrode or the referenceelectrode (FIG. 2). The ultimate purpose of the measurement block is tomeasure a parameter (such as voltage or current) that can be used todetermine the impedance or resistance between the measurement electrodeand the reference electrode. The measurement block is connected to thecontrol block.

[0017] The control block is connected to the user interface block (ifpresent), the data storage block (if present), the result presentationblock, the voltage generator block and the measurement block. Thecontrol block sets the voltage generated by the voltage generator block.The control block uses information received from the measurement blockto detect the break-through effect, and the resistance asymmetry. Thecontrol block can store and retrieve information in the data storageblock (if present). The control block informs the user of the results ofthe measurements through the result presentation block. The resultpresentation block may be generate a visual or audio indication toinform the user of the result i.e. the state of health of the internalorgan obtained by the control block.

Description of Operation

[0018] After a great deal of experimental work the inventor has foundthat an apparatus broadly in accordance with the invention may beoperated as described below to obtain reliable results.

[0019] Technique 1: AC evaluation

[0020] The calibration electrode is placed in contact with the relevantskin area corresponding to the internal organ of a subject the sate ofhealth of which is to be determined. The reference electrode is placedin contact with any other skin area, usually the hand of the subject.The control block uses the voltage generator block to generate an ACsignal of specific frequency and magnitude between the calibration andreference electrodes. The control block determines the impedance betweenthe electrodes via the measurement block. The control block stores theimpedance value in the data storage block (referred to as “calibrationimpedance”). The control block signals that the calibration impedancehas been determined via the result presentation block. The calibrationelectrode is removed and the measurement electrode is placed on the skinarea undergoing investigation. The control block uses the voltagegenerator block to generate an AC signal of similar frequency andmagnitude between the calibration and reference electrodes.

[0021] The control block determines the ratio between the calibrationimpedance and the impedance measured with the measuring electrode andconverts this ratio to an indication of the state of health of theinternal organ The control block displays the result on the resultpresentation block (e.g. on a disease intensity percentage scale).

[0022] Conveniently the result is displayed in percentage format,calculated according to the following equation:

% Disease=(1−I _(measurement) /I _(reference))×100; or

% Disease=(1−R _(reference) /R _(measurement))×100.

[0023] Various percentage ranges corresponding to different states ofhealth of the organ. Typically 0 to 40% indicates a healthy state, 40 to60% indicates the upper limits of the healthy state, 60 to 80% indicatesa sub-acute state, and 80 to I100% indicates an acute condition of theinternal organ in question.

[0024] Technique 2: DC evaluation

[0025] The reference electrode is placed in contact with any skin areaThe measurement electrode is placed in contact with a specific skin spotcorresponding with an internal organ the state of health of which is tobe determined. The control block uses the voltage generator block togenerate a DC potential difference between the electrodes. The controlblock determines the resistance between the electrodes via themeasurement block. The control block adjusts the DC potential differenceand checks the resistance until the resistance falls below a certainthreshold or suddenly starts decreasing rapidly (break-through effect).The control block checks the resistance until a stable value is reached.The control block stores this resistance value in the data storage block(referred to as “reference resistance”).

[0026] The control block inverts the polarisation of the measurement andreference electrodes with respect to each other and uses the voltagegenerator block to apply a DC potential across the electrodes. Thecontrol block determines the resistance between the electrodes via themeasurement block (referred to as “measurement resistance”).

[0027] The control block determines the ratio between the “measurementresistance” and the “reference resistance” and calculates the intensityof disease from this ratio. The following equation is used for thecalculation:

% Disease=(1−I _(measurement) /I _(reference))×100; or

% Disease=(1−R _(reference) /R _(measurement))×100

[0028] The control block displays the result on the result presentationblock (e.g. on a disease intensity percentage scale).

[0029] Conveniently the result is displayed in percentage format, withvarious percentage ranges corresponding to different state of health ofthe organ. Typically 0 to 40% indicates a healthy state, 40 to 60%indicates the upper limits of the healthy state, 60 to 80% indicates asub-acute state, and 80 to 100% indicates an acute condition of theinternal organ in question.

[0030] For best break-through effect induction the reference resistancemeasurement should be made with the measurement electrode polarisednegatively with respect to the reference electrode, although with higherpotential differences between the electrodes it is believed that thebreak-through effect may also be observed if the polarity is inverted.

[0031] When using the DC technique, if the internal organ is not healthya higher resistance will be measured with the measurement electrodepolarised positively with respect to the reference electrode than withthe measurement electrode polarised negatively with respect to thereference electrode e.g. 300 kΩ as opposed to 30 kΩ. Similarly, whenusing the AC technique, the measurement obtained using the measurementelectrode will have an impedance reading which is higher than that ofthe measurement obtained using the calibration electrode.

[0032] It is also possible to use an AC signal when using the DCtechnique

[0033] Although both the AC and DC evaluation techniques are effective,for thin skin regions of the body, such as the ear auricle, the DCevaluation technique is preferred, while for thicker skin areas of thebody, such as the feet, the AC method is preferred as thicker skin areasrequire higher voltages for the breakthrough effect to occur, whichcould be painful for the subject.

[0034] The inventor believes that an apparatus such as that describedabove, uses new measurement technologies and ratiometric techniques andachieves consistent and repeatable diagnostic results which areindependent of various physiological differences between individuals,the emotional state of a patient, muscular tension and the measurementtime. The results depend on the intensity of the disease, the effect ofpressure is insignificant.

EXAMPLES

[0035] Example 1:

[0036] In a first test in which a gastric ulcer was diagnosed, thefollowing results were obtained:

[0037] Auricular projection areas (thin skin−DC measurement): referenceresistance=10 kΩ;

[0038] →Stomach projection area: measurement resistance=200 kΩ; i.e. 95%of disease activity

[0039] →Healthy organ projection areas: measurement resistance=10-25 kΩie 0-60% of disease activity

[0040] Pedal projection areas (thick skin−AC measurement): Referenceresistance=15 kΩ(at 250 Hz)

[0041] →Stomach projection area: measurement resistance=300 kΩi e 95% ofdisease activity

[0042] →Healthy organ projection areas: measurement resistance=15-37.5kΩl i.e. 0-60% of disease activity

[0043] Example 2

[0044] Pyelonephritis (kidney infection)

[0045] Auricular projection areas (thin skin−DC measurement): Referenceresistance=10 kΩ

[0046] →Kidney projection area: measurement resistance=100 kΩi.e. 90% ofdisease activity

[0047] →Healthy organ projection areas: measurement resistance=10-25kΩi.e. 0-60% of disease activity

[0048] Pedal projection areas (thick skin−AC measurement): Referenceresistance=10 kΩ(at 250 Hz)

[0049] →Kidney projection area: measurement resistance=100 kΩi.e. 90% ofdisease activity

[0050] →Healthy organ projection areas: measurement resistance=10-25kΩi.e. 0-60% of disease activity

DESCRIPTION OF THE DRAWINGS

[0051]FIG. 1 shows, in schematic block diagram representation, anapparatus for evaluation of skin impedance variations and state ofhealth of a corresponding internal organ, using the DC or AC techniqueof measurement, broadly in accordance with the invention;

[0052]FIG. 2 shows, in schematic block diagram representation, analternative implementation of an apparatus for evaluation of skinimpedance variations and state of health of a corresponding internalorgan, using the DC or AC technique of measurement, broadly inaccordance with the invention;

[0053]FIG. 3 shows, in schematic block diagram representation, anapparatus for evaluation of skin impedance variations and state ofhealth of a corresponding internal organ, using the DC or AC techniqueof measurement, in accordance with the invention;

[0054]FIG. 4 shows, in schematic circuit diagram representation, a powersupply unit according to FIG. 3,

[0055]FIG. 5 shows, in schematic circuit diagram representation, acontrol block and a user interface block according to FIG. 3;

[0056]FIG. 6 shows, in schematic circuit diagram representation, aresult presentation block according to FIG. 3;

[0057]FIG. 7 shows, in schematic circuit diagram representation, avoltage generator block and a measurement block according to FIG. 3;

[0058]FIG. 8 shows, in schematic circuit diagram representation, a datastorage block according to FIG. 3;

[0059]FIG. 9 shows a simplified flow diagram of the software used in themicrocontroller in the control block in FIG. 5;

[0060]FIG. 10 shows, in graphic representation, the breakthrough effectobtained using the apparatus of the invention in DC measurement mode;

[0061]FIG. 11 shows, in graphic representation, the dependence of skinresistance on applied voltage for a skin spot corresponding to a healthyorgan (FIG. 11a) and a skin spot corresponding to a diseased organ (FIG.11b), obtained when applying the technique of the invention using the DCmeasurement technique;

[0062]FIG. 12 shows, in graphic representation, the dependence of skinimpedance on applied frequency, when applying the technique of theinvention using the AC measurement technique;

[0063]FIG. 13 shows, in graphic representation, skin spots on a humanear auricle corresponding to internal organs; and

[0064]FIG. 14 shows, in graphic representation, skin zones on the soleof a human foot corresponding to particular internal organs.

[0065] In the figures reference numeral 1 broadly indicates an apparatusfor determining the state of health of an internal organ of a subject bythe impedance variation evaluation method, broadly in accordance withthe invention

[0066] The apparatus 1 includes a voltage generator block 5 whichgenerates a potential difference between a measurement 11.1 orcalibration 11.2 electrode and a reference electrode 11.3. The voltagegenerator block 5 is connected to and controlled by the control block 2.The measurement block 6 is connected to the measurement electrode 11.1or calibration electrode 11.2 and the reference electrode 11.3.

[0067] In FIG. 2 reference numeral 1.2 broadly indicates an alternativeapparatus for determining the state of health of an internal organ of asubject by the impedance variation evaluation method, broadly inaccordance with the invention.

[0068] The voltage generator block 5 generates a potential differencebetween the measurement 11.1 or calibration electrode 11.2 and thereference electrode 11.3. The voltage generator block 5 is connected toand controlled by the control block 2. The measurement block 6 isconnected to the measurement electrode 11.1 or calibration electrode11.2 and the reference electrode 11.3.

[0069] The measurement block 6 determines the impedance between themeasurement electrode 11.1 or calibration electrode 11.2 and thereference electrode 11.3. Alternatively the voltage generator block 5can be connected through the measurement block 6 to the measurementelectrode 11.1 or the calibration electrode 11.2 or the referenceelectrode 11.3. The ultimate purpose of the measurement block 6 is tomeasure a parameter (such as voltage or current) that is dependent onthe impedance or resistance between the measurement electrode 11.1 orcalibration electrode 11.2 and the reference electrode 11.3. Themeasurement block 6 is connected to the control block 2.

[0070] The control block 2 is connected to the user interface block 8,the data storage block 3, the result presentation block 7, the voltagegenerator block 5 and the measurement block 6. The control block 2 setsthe voltage generated by the voltage generator block 5. The controlblock 2 uses information received from the measurement block 6 to detectthe breakthrough effect and the resistance asymmetry. The control block2 can store and retrieve information in the data storage block 3. Thecontrol block 2 informs the user of the results of the measurementsthrough the result presentation block 7. The result presentation block 7may generate a visual or audio indication to the user of the result i.e.the state of health of the internal organ, obtained by the control block2.

[0071] Referring to FIG. 3, an electrodermal diagnostic unit 1 isprovided which is primarily intended for use in diagnosing internalorgan pathology in humans through electric stimulation and impedancemeasurement of remotely located skin spots.

[0072] In the electrodermal diagnostic unit 1 the control block 2displays instructions to the operator through LCD display 37 exclusivelyor in combination with a video monitor connected to the video displayunit 13 or a television set connected to the UHF modulator unit 10.Lists of organs that can be diagnosed are displayed on the monitor ortelevision set. The operator selects internal organs to diagnose via thekeypad 9.

[0073] The control unit 2 selects a method of diagnosis based on thelocation of the skin spot/zone to be investigated. Two methods ofdiagnosis, are available specifically alternating current measurement(AC measurement) or direct current measurement (DC measurement). ACmeasurement is better suited to areas with thicker skin such as thesoles of the feet. DC measurement is better suited to areas with thinskin such as the ear.

[0074] The control unit 2 displays a picture of the region to beinvestigated (such as the foot or ear). A flashing zone or spotindicates where the measuring electrode 11.1 must be placed by theoperator. The control unit 2 controls the voltage generator block 5through an optical link to execute the selected test.

[0075] For DC measurement: The voltage generator block 5 generates asmall constant potential difference between the measurement electrode11.1 and the reference electrode 11.3, with the measurement electrodepolarized negatively with respect to the reference electrode. Thecurrent is continuously monitored by the control block 2 using themeasurement block 6 and when the current rises above a preset threshold,it is assumed that both probes are in contact with the skin. Thepotential difference between the probes is slowly increased and thecurrent through the probe measured continuously. The skin resistance iscalculated by dividing the value of the potential applied to the probesby the value of the measured current running through the probes. When asudden significant drop in this resistance is detected (see FIG. 9 foralgorithm) the potential difference between the probes is continuouslyadjusted so as to maintain the measured current through the probes at apredetermined level. This continues until the rate of change in skinresistance falls below a predetermined level. The value of the potentialdifference at this time is stored by the control block 2 in the datastorage block 3. The control block 2 uses the voltage generator block toapply the same potential difference between the probes with oppositepolarization (the measurement electrode positively polarized withrespect to the reference electrode). The current is continuouslymeasured. The ratio (measured current)/(preset current) is believed togive an indication of the degree of pathology in a particular organ. Ifthis ratio is close to zero, the relevant organ is believed to bediseased. If this ratio is greater than 0.6 then the relevant organ isbelieved to be healthy. The closer this ratio is to zero, the greaterthe degree of pathology (e.g. cancer) is believed to be present in theorgan.

[0076] The control block 2 monitors the current via the measurementblock 6 and displays the test result on the LCD display 37 on a diseasepercentage scale until the operator presses the foot pedal 12. Thecontrol block stores the test result in the data storage block 3, andactivates the buzzer 36 to indicate the completion of the test.

[0077] For AC measurement: The operator places the reference electrode11.3 and the calibration electrode 11.2 on the skin of the subject whenprompted via the LCD display 37. The voltage generator block 5 generatesa small constant potential difference between the electrodes 11.2,11.3.The current is continuously monitored and when the current rises above apreset threshold, it is assumed that both probes are in contact with theskin. An sinusoidal alternating voltage is now applied between theelectrodes. The current is monitored continuously by the control block 2using the measurement block 6 and the voltage adjusted until the currentreaches a preset level. This process is referred to as calibration

[0078] The control unit 2 displays a picture of the region to beinvestigated (typically the foot) on the video monitor or televisionscreen using the result presentation block. The control unit 2 displaysa message on the LCD display 37 informing the operator that themeasuring electrode 11.1 and the reference electrode 11.3 must now beused. A flashing zone or spot indicates where the measuring electrode11.1 must be placed by the operator. The current is continuouslymeasured. The ratio (measured current)/(preset current) is believed togive an indication of the degree of pathology in a particular organ. Ifthis ratio is close to zero, the relevant organ is believed to bediseased. If this ratio is greater than 0.6 then the relevant organ isbelieved to be healthy. The closer this ratio is to zero, the greaterthe degree of pathology (e.g. cancer) is believed to be present in theorgan. The control block 2 monitors the current via the measurementblock 6 and displays the test result on the LCD display 37 on a diseasepercentage scale until the operator presses the foot pedal 12. Thecontrol block stores the test result in the data storage block 3, andactivates the buzzer 36 to indicate the completion of the test.

[0079] The control unit 2 consists of a microcontroller 16 (typically an8051). An oscillator 28 provides a clock signal for the microcontroller16. A standard adress latch (11) configuration is used to create a 16bit adress bus (11.1,16.3) which connects to 32K random access memory 56and 32K read only memory 57. A bidirectional data bus 16 1 transportsdata to and from the microcontroller 16. The microcontroller 16interfaces which a keypad 9 using keypad interface 17, (typically74HC922)

[0080] The electrodes are galvanically isolated 55 from the main circuitby a transformer 43 in the voltage generator block 5. The measurementblock 6 is optically isolated from the main circuit by optocouplers51,52,53,54. A sinusoidal voltage applied to the primary coil oftransformer 43.1 is stepped up by the secondary coil 43.2. Voltagedoubling circuit 44 doubles and rectifies the sinusoidal output of coil43.2 so that a constant voltage appears over capacitor 38. When relay 40is off an alternating voltage is fed through to the relay 42. When relay40 is on, the constant voltage over capacitor 38 is fed through to therelay 42.. Relay 42 is used to switch the polarity of the signal fromrelay 40. This combination of relay 42 and 40 is used to set the voltagebetween the probes to an alternating voltage or a constant voltage andallows the polarity of the probes to be reversed.

[0081] The primary coil 43.1 of then transformer 43 is driven by anopamp 41 which is used in inverter amplifier mode. A programmablesinewave generator 39 (typically ML2036) provides the input signal tothe opamp 41. Sinewave generator 39 is controlled by the microcontroller16 via lines 22.1, 22.3, 22.4. The frequency is digitally programmed viathis serial bus. The magnitude of the output sinusoidal signal (halfpeak to peak) is equal to the voltage on the output 24.1 of a digital toanalogue converter 24. The output voltage of the digital to analogueconverter 24 is set via bus 16.1 by the microcontroller 16.

[0082] The current is measured using the measurement block 6. When thecircuit between the electrodes is closed by an impedance such as thehuman body, current is conducted through the electrodes to ground viameasuring resistor 46 The voltage appearing over this resistor withrespect to ground is therefore proportional to the current through theprobes. An opamp buffer 45 feeds the signal to the precision rectifierformed by the opamps referred to by numerals 47 and 48.These extract theabsolute value of the signal which is fed into a serial analogue todigital converter (ADC) 49. The ADC 49 communicates with themicrocontroller 16 via a serial bus consisting of lines 22.1, 22.2 and22.3 through an optical link provided by three optocouplers 52,53,54. Azero crossing detector 50 detects the polarity of the voltage over themeasuring resistor 46 and transmits this information as a binary one orzero to the microcontroller 16 through an optocoupler 51. When analternating voltage is applied to the electrodes, current is measured atevery voltage peak. The microcontroller 16 waits for a zero to onetransition to occur on the output 22.5 of optocoupler 51. Themicrocontroller 16 waits for a time period equal to one quarter of theperiod of the output voltage frequency before requesting a conversionfrom the analogue to digital converter 49.

[0083] The microcontroller displays relevant information on a monitorthrough the video display unit 13. A dual port ram 30 contains a bitmapped version of the screen. The microcontroller 16 can read and writedata to the dual port ram 30 through a data bus 16 1 using control lines16.6 and 16.7 and the adress bus, referred to by numerals 11.1 and 16 3.A field programmable gate array (FPGA) 25 uses counters and shiftregisters to sequentially read bytes of screen data and to write redgreen and blue (RGB) pixel information as well as vertical andhorizontal retrace information to an RGB to PAL encoder 31. A universalsync generator 33 generates PAL video standard synchronization pulses.These pulses are locked to the mail system clock using a phase lockedloop 34. The pixel clock is derived from the main system clock 16.5using counters in the FPGA 25. The pixel clock is used to read andserialize data at the correct rate and in the correct manner from thedual port ram 30 so that the bit streams fed to the RGB to PAL encodercan be encoded into a PAL standard composite sync video signal that canbe fed directly into the video input 31.1 of a standard video monitor.

[0084] The UHF modulator unit 10 converts the composite sync videosignal to an ultra high frequency signal that can be directly fed intothe aerial port 35.1 of a television set. An integrated UHF modulator 35modulates the composite sync PAL signal from the video display unit to afrequency determined by external components.

[0085] Power is delivered to the circuit by the power supply block 4. Atransformer 14.1 with primary coupling connected to mains and secondarycoupling connected to rectifier bridge 14.2 converts the mains 220VAC to7.2 VAC. The output of the rectifier is fed into 5V regulator 14.3. Amonolithic voltage inverter 15.1 typically a MAX660 generates a −5Vsupply from the main 5V supply.

[0086] The power supplied to the voltage generator block 5 and themeasurement block 6 is galvanically isolated from the main power supply.DC to DC converter 15.2 (typically NMA0505) is used to supply +5V and−5SV to the isolated patient interface circuitry.

[0087]FIG. 10 shows a graph of voltage over a period of time when thebreakthrough effect (x) is achieved. At the point of breakthrough (x) asudden and significant decrease in resistance occurs, and thus a suddenand significant decrease in voltage is also observed. The referencevalue is measured once the voltage stabilises after the brekthrougheffect.

[0088]FIGS. 11a and 11 b show how resistance is affected when an organis diseased. In FIG. 11a, the two curves represent resistance values atdifferent voltages for a healthy organ, while FIG. 11b shows two curvesof resistance values at different voltages for an unhealthy organ. Lines50 represent the reference resistance values, and lines 52 represent themeasurement resistance values. FIG. 11b shows two curves of resistancevalues at different voltages for an unhealthy organ. When an organ ishealthy, the reference and measurement resistance values are similar,but as the state of disease of the organ increases, so the measurementvalue increases and the greater the difference between the reference andmeasurement values.

[0089] Similarly, FIG. 12 shows how the measurement impedance changeswhen an organ is diseased. Line 56 shows reference or resistance valuesat different frequencies. Line 58 shows measurement resistance valuesfor a healthy organ whereas line 60 shows measurement resistance valuesfor an unhealthy organ. The more diseased an organ becomes, the higherthe resistance of the measurement values, and consequently the greaterthe difference between the measurement and reference values.

[0090] Referring to FIGS. 13 and 14, the measurement or calibrationelectrodes are placed on one of the spots indicated in order to obtain adiagnosis of a specific organ The spot on which the electrode is placeddepends on the specified organ, and Tables 1 and 2 set out below showthe organs to which the numbered spots refer. TABLE 1 Number on FIG. 13Portion of Body  1 Heart (R)  2 Thyroid Gland  3 Lungs (Upper Lobe)  4Lungs  5 Oesophagus (Cardia)  6 Stomach  7 Liver (Left Lobe) (R)  8Liver (Right Lobe) (L)  9 Spleen (R) 10 Kidneys 11 Pancreas (R) 12 GallBladder (L) 13 Duodenum (L) 14 Transverse Colon 15 Left Colon (R) 16Right Colon (Appendix) (L) 17 Small Intestine 18 Ureter 19 Bladder 20Prostate 21 Distal Colon 22 Mammary Gland 23 Ovary & Adnexa Uteri 24Uterus 25 Pons 26 Thalamus 27 Hypothalamus 28 Hypophysis 29 Cortex(Frontal Lobe) 30 Midcortex 31 Cortex (Posterior) 32 Cerebellum 33Medulla Oblongata 34 Cervical Spine 35 Thoracic Spine 36 Lumbo-SacralSpine 37 Shoulder 38 Elbow 39 Wrist 40 Metacarpus 41 Fingers 42 Hip 43Knee 44 Ankle 45 Metatarsus 46 Toes

[0091] TABLE 2 Number on FIG. 14 Portion of Body  1 Brain  2 Pituitary 3 Thyroid Gland  4 Oesophagus  5 Lungs  6 Heart  7 Liver  8 CardiacSphincter  9 Stomach 10 Spleen 11 Gall Bladder 12 Adrenal Glands 13Pancreas 14 Duodenum 15 Colon 16 Kidneys 17 Small Intestine 18 Ureters19 Fallopian Tubes 20 Ovaries 21 Bladder 22 Appendix

[0092] The invention is not limited to the precise constructionaldetails disclosed in this specification and it will be clear to thoseskilled in the art that the above principles may be applied to produceother apparatus embodying these principles. Specifically, the apparatusas described uses impedance and resistance measurements to calaculatethe state of health of the organ in question, but it will be clear tothose skilled in the art that other values which are either directly orindirectly proportional to resistance or impedance may be used asmeasurements and in the calculations.

1. A method for diagnosing a state of health of at least a portion of ahuman or animal body, the method including the following steps. applyingto the body a potential difference between a reference electrode incontact with the body and a measurement electrode also in contact withthe body; controlling either a current value or a voltage value suchthat the current through the electrodes or the voltage between theelectrodes remains within predefined limits; monitoring at least acurrent or a voltage, such that the current or voltage through orbetween the electrodes is determinable, until such time as a sudden andsignificant change in the monitored current or voltage is observed;measuring a reference value which is a current, resistance or voltagevalue which is dependent on resistance between the electrodes; alteringthe potential difference between the electrodes so that the polarity ofthe electrodes is inverted; measuring a measurement value which is acurrent, resistance or voltage value which is dependent on resistancebetween the electrodes; and relating the reference and measurementvalues to the state of health of the portion of the body.
 2. A method asclaimed in claim 1 , wherein the controlled voltage or current is avoltage between the electrodes or a current through the electrodes.
 3. Amethod as claimed in either of claims 1 or 2, wherein the monitoredcurrent and/or voltage is the current through the electrodes or thevoltage between the electrodes.
 4. A method as claimed in any one ofclaims 1 to 3 , wherein the current is monitored if the voltage iscontrolled.
 5. An apparatus as claimed in claim 4 , wherein the currentis monitored until a sudden and significant increase in current isobserved.
 6. An apparatus as claimed in any one of claims 1 to 3 ,wherein the voltage is monitored if the current is controlled.
 7. Anapparatus as claimed in claim 6 , wherein the voltage is monitored untila sudden and significant decrease in voltage is observed.
 8. A method asclaimed in any one of claims 1 to 7 , wherein a resistance between theelectrodes is monitored.
 9. A method as claimed in claim 8 , wherein theresistance is monitored until a sudden and significant decrease inresistance is observed.
 10. A method as claimed in any one of claims 1to 9 , wherein the reference value is measured when the monitoredcurrent, voltage or resistance is substantially constant.
 11. A methodas claimed in any one of the preceding claims, wherein prior tomeasurement of the reference value the voltage over the electrodes isadjusted until the current through the electrodes measures a preselectedvalue.
 12. A method as claimed in claim 11 , wherein the voltage isadjusted until the current reading is between 10 and 50 μA
 13. A methodas claimed in claim 12 , wherein the voltage is adjusted until thecurrent reading is between 20 and 30 μA.
 14. A method as claimed in anyone of claims 1 to 10 , wherein prior to measurement of the referencevalue the current is adjusted until the voltage measures a preselectedvalue.
 15. A method as claimed in claim 14 , wherein the current isadjusted so that the voltage does not exceed 30 V.
 16. A method asclaimed in any one of claims 1 to 15 , wherein the reference value isthe current through the electrodes, the skin resistance between theelectrodes, or the voltage between the electrodes.
 17. A method asclaimed in any one of claims 1 to 16 , wherein the measurement value isthe current through the electrodes, the resistance between theelectrodes, or the voltage between the electrodes.
 18. A method asclaimed in any one of the preceding claims, wherein the measurementelectrode is placed in contact with a zone of skin on the bodycorresponding to the portion of the body to be diagnosed.
 19. A methodas claimed in any one of the preceding claims, wherein the measurementelectrode is a point electrode
 20. A method as claimed in any one of thepreceding claims, wherein the measurement electrode is negativelypolarised with respect to the reference electrode when the potentialdifference is first applied to the body prior to the reference valuebeing measured.
 21. A method as claimed in any one of the precedingclaims, wherein the portion of the body is an internal organ of the bodywhich corresponds to the part of the body to which the potentialdifference is applied.
 22. A method as claimed in any one of thepreceding claims, wherein the potential difference is applied to theskin of the body.
 23. A method as claimed in claim 22 , wherein thepotential difference is applied to the area of the skin corresponding tothe internal organ being diagnosed.
 24. A method as claimed in any oneof the preceding claims, wherein the state of health of the portion ofthe body is expressed as a ratio of the reference and measurementvalues.
 25. An apparatus for diagnosing a state of health of at least aportion of a human or animal body, the apparatus including: anelectrical signal generating means to which at least measurement andreference electrodes are connectable; a means for measuring at least onereference parameter from a group including voltage, current andresistance; a controlling means which in use, when a potentialdifference is applied between the electrodes, monitors the referenceparameter until there is a significant and sudden change in thereference parameter, whereafter a recording means records a measuredvalue of the reference parameter, whereafter the controlling meanschanges the voltage between the electrodes such that the polarity of theelectrodes is inverted, whereafter a measured value of a measurementparameter is measured and recorded, the measurement parameter beingselected from the group including voltage, current and resistance; meansfor comparing the reference and measurement values; and means forcommunicating the comparison to an operator of the apparatus.
 26. Anapparatus as claimed in claim 25 , which includes reference andmeasurement electrodes.
 27. An apparatus as claimed in either of claims25 or 26, wherein the reference parameter is the voltage between theelectrodes.
 28. An apparatus as claimed in claim 27 , wherein thevoltage is monitored until a sudden and significant decrease in voltageis observed.
 29. An apparatus as claimed in claim 25 or 26 , wherein thereference parameter is the current through the electrodes.
 30. Anapparatus as claimed in claim 29 , wherein the current is monitoreduntil a sudden and significant increase in current is observed.
 31. Anapparatus as claimed in claim 25 or 26 , wherein the reference parameteris the resistance between the electrodes.
 32. An apparatus as claimed inclaim 31 , wherein the resistance is monitored until a sudden andsignificant decrease in resistance is observed, whereafter a resistancevalue is recorded.
 33. An apparatus as claimed in any one of claims 25to 32 , wherein the current through the electrodes or voltage across theelectrodes is adjusted until there is a sudden and significant change inthe reference parameter.
 34. An apparatus as claimed in any one ofclaims 25 to 33 , wherein the value of the reference parameter is onlymeasured once the reference parameter is substantially constant.
 35. Anapparatus as claimed in either of claims 27 or 28, wherein themeasurement parameter is the voltage between the electrodes.
 36. Anapparatus as claimed in either of claims 29 or 30, wherein themeasurement parameter is the current through the electrodes.
 37. Anapparatus as claimed in either of claims 31 or 32, wherein themeasurement parameter is the resistance across the electrodes.
 38. Anapparatus as claimed in any one of claims 25 to 37 , wherein a switchingmeans is provided to invert the polarity of the electrodes.
 39. Anapparatus as claimed in any one of claims 25 to 28 wherein prior tomeasurement of the reference value the current through the electrodes isadjusted until the voltage over the electrodes measures a preselectedvalue.
 40. An apparatus as claimed in claim 39 , wherein the current isadjusted so that the voltage does not exceed 30 V.
 41. An apparatus asclaimed in any one of claims 25, 26, 29 and 30, wherein prior tomeasurement of the reference value the voltage over the electrodes isadjusted until the current through the electrodes measures a preselectedvalue.
 42. An apparatus as claimed in claim 41 , wherein the voltage isadjusted until the current reading is between 10 and 50 μA.
 43. Anapparatus as claimed in claim 41 , wherein the voltage is adjusted untilthe current reading is between 20 and 30 μA.
 44. An apparatus as claimedin any one of claims 26 to 43 , wherein the measurement electrode is apoint electrode.
 45. An apparatus as claimed in any one of claims 26 to43 , wherein the measurement electrode has a clip portion for attachingthe electrode to an auricle of an ear.
 46. An apparatus as claimed inany one of claims 25 to 45 , wherein the measurement electrode isnegatively polarised with respect to the reference electrode when thefirst potential difference is applied across the electrodes prior to thereference parameter being measured.
 47. An apparatus as claimed in anyone of claims 25 to 46 , wherein the state of health of the diagnosedportion of the body is expressed as a ratio of the reference andmeasurement values.
 48. An apparatus as claimed in any one of claims 25to 47 , wherein the comparison of the reference and measurement valuesis communicated to the operator visually or audibly.
 49. An apparatus asclaimed in any one of claims 47 or 48, wherein the state of health ofthe diagnosed portion is communicated as being either healthy, normal,sub-acute or acute, depending on the ratio of the measurement andreference values.
 50. An apparatus as claimed in any one of claims 25 to49 , which is connectable to a computer or television.
 51. An apparatusas claimed in any one of claims 25 to 50 , wherein the portion of thebody to be diagnosed can be selected.
 52. An apparatus as claimed inclaim 51 , which includes means for detecting whether or not themeasurement electrode has been placed on the zone of skin correspondingto the selected portion of the body.
 53. A method of diagnosing a stateof health of at least a portion of a human or animal body, the methodincluding the following steps: applying an AC signal to the body whichpasses from a first electrode in contact with the body to a secondelectrode also in contact with the body, one of the electrodes being acalibration electrode in contact with a zone of skin in the vicinity ofa zone of skin on the body corresponding to the portion of the body tobe diagnosed; measuring a first reference reading which is dependent onthe magnitude of the impedance between the electrodes; substituting ameasurement electrode for the calibration electrode, the or measurementelectrode being in contact with the zone of the skin which correspondsto the portion of the body to be diagnosed; measuring a comparativereading which is also dependant on the magnitude of the impedancebetween the electrodes, and relating the reference and comparativereadings to the state of health of the portion of the body.
 54. A methodas claimed in claim 53 , wherein the reference reading is the impedanceacross the electrodes.
 55. A method as claimed in claim 53 or 54 ,wherein the comparative reading is the impedance across the electrodes.56. A method as claimed in any one of claims 53 to 55 , wherein themeasurement electrode has a different skin contact surface area than thecalibration electrode.
 57. A method as claimed in claim 56 , wherein thecalibration electrode has a larger skin contact surface area than themeasurement electrode.
 58. A method as claimed in any one of claims 53to 57 , wherein the portion of the body is an internal organ of the bodywhich corresponds to the part of the body to which the AC signal isapplied.
 59. A method as claimed in any one of claims 53 to 58 , whereinthe AC signal is applied to the skin of the body.
 60. A method asclaimed in claim 58 or 59 , wherein the AC signal is applied to the areaof the skin corresponding to the internal organ being diagnosed
 61. Amethod as claimed in any one of claims 53 to 60 , wherein the frequencyof the AC signal is 250 Hz.
 62. A method as claimed in any one of claims5 3 to 6 1, wherein the state of health of the portion of the body isexpressed as a ratio of the comparative and reference readings.
 63. Anapparatus for diagnosing a state of health of at least a portion of ahuman or animal body, the apparatus including: an AC signal generator towhich at least two electrodes are connectable; a measuring means whichin use measures a parameter which depends on the magnitude of theimpedance between the electrodes; a recording means for recording atleast two values of the parameter; a comparison means for comparing thetwo values; and a communicating means for communicating the comparisonof the values to an operator of the apparatus.
 64. An apparatus asclaimed in claim 63 , which includes reference, calibration andmeasurement electrodes.
 65. An apparatus as claimed in claim 64 ,wherein the calibration electrode has a larger skin contact surface areathan the measurement electrode.
 66. An apparatus as claimed in any oneof claims 63 to 65 , wherein the frequency of the AC signal is 250 Hz.67. An apparatus as claimed in any one of claims 63 to 66 , wherein thestate of health of the portion of the body is expressed as a ratio ofthe two values.
 68. An apparatus as claimed in any one of claims 63 to67 , wherein the portion of the body to be diagnosed can be selected.69. An apparatus as claimed in claim 68 , which includes means fordetecting whether or not the measurement and calibration electrodes havebeen placed on the zone of skin corresponding to the selected portion ofthe body.
 70. An apparatus for diagnosing a state of health of at leasta portion of a human or animal body, the apparatus including: anapparatus as claimed in any one of claims 25 to 52 ; and an apparatus asclaimed in any one of claims 63 to 69 .
 71. A method or apparatus,substantially as herein described and illustrated.
 72. A new method or anew apparatus substantially as herein described.